Effects of alcohol aqueous extract from Rhodiola rosea L. roots on learning and memory.

The effect of alcohol-aqueous extract (1:1) from Rhodiola rosea L. roots on the processes of learning and memory is studied on rats. Several methods of active avoidance with negative and positive reinforcements are used, as well as of passive avoidance. Using the maze-method with negative (punitive) reinforcement, it has been found that Rhodiola extract in a single dose of 0.10 ml per rat essentially improves learning and retention after 24 hours. Significant improvement of the long-term memory is also established in memory tests after 10-day treatment with the same dose of the extract. In the other two doses tested (0.02 and 1.0 ml per rat) the extract has no substantial effect on learning and memory. In a dose of 0.10 ml per rat the Rhodiola extract had a favourable effect on the training process using the "staircase" method with positive (food) reinforcement as well. With the other methods used (active avoidance method with negative reinforcement "shuttle-box" and passive avoidance methods "step down" and "step through") Rhodiola extract in the dose used (0.10 ml per rat) had no substantial effect on learning and memory (a certain deterioration of the training process was even observed using the "shuttle-box" method, while the "step-down" method resulted in deterioration of the memory). The great significance of the method used for studying the effects of the pharmacological agents on learning and memory for the results obtained is evident.